OPERATIONAL EXPERIENCE OF AN OXY-FUEL FIRED GLAS S MELTER USING AN IMPROVED SILICA CROWN AN D WIDE FLAM E BURNERS Alonso Gonzale z R., Gmpo Pavisa, Naucalpan , MEX , Mexico Wladimir Sanniento- Darkin , Praxair , Inc. , Tonawanda, NY , USA John T . Bro w n , GMIC, Corni ng , NY , USA Len Switzer , Praxa ir , Inc ., Burr Ridge , lL , USA Euan Evenso n , Praxair, In c ., Tonawanda, NY, USA Sho Kobayashi, Praxair , Inc., Danbury , CT, USA Cu auhtemoc Lagos, Praxa ir Mexico S. de R.L. de C.V., Mexico, D.F., Mexico ABSTRACT The implementation of oxy-fuel firing technology in g lass furnace s has become a technically feasible solution for producing g lass over the last 2 decades. However , challenges do still exist concerning refractmy corrosion and fumace life. It has been recognized that the high concentrat ion of sodium species in an oxy -fu el fired furnace can lead to acce lerated corrosion of the furnace crown. In this paper, the details of an operatio nal campaign f or an oxy - fue l fired conta iner glass furna ce are presented and discussed. The furnace crown was cons truc ted w ith a low lime s ilica brick (0.8% CaO) which was expected to offer s up eri or cm To sion re s is tanc e to a conve ntiona l s ilica crown. The fumace al so employed ultr a low -mome ntum , Wide Fl ame bume rs to he lp minimi ze vo latili z ati on from the me lt s urface. Th e ex pe ri ence from this furnace campa ign indicates that the crown mate rial and bumers both met perf ormance expectations and sho uld be considered as part of a robust operatin g so l ution for container glass ma nufacturers . INTRODUCTION The fundament al pi cture of a continuous glass melting opera tion has changed little in the past !50 years. Although the concept of an all refi·actmy, rev e rb era tot y f umace with continual operation has not changed , great strides have been made in the materials of co nstmction, mainte nance an d operation of these systems. One operational change which has greatly changed the operation and environmental footprint of g lass producti o n is the use of industrially pure oxygen in place of air. Th e conversio n of typical air- fired g lass furnaces to oxy-fuel firing has led to reductions in specific energy requirements , reduced emi ssio ns of air pollutant s, in creased specific pull rates , simplified furnace co ns truction , and improved operation a l consi s tenc y and g la s s quality. However , oxy-fuel tec hn o lo gy has also forced g lass makers to consider alternative m ate ri a ls of co n stm ction , creative constmction , operati onal changes and robust maintenance programs to addre s s the challenges of using industrially pure oxy gen. The primary goa l in op timiz ing the design, operation and maintenance of an oxy-fu el fired glass furnace has been extending the life of superstructure refractories, particularly the fumac e cr own . Traditional air-fired furnaces utilize silica brick for crown construction due to its relativ ely low density, thetmal conduct ivity, corros ion characteristic s, an d moderate cost . However, silica crown bricks applied to oxy-fuel fumaces sometimes experience acce lerated corrosion, , vatying greatly with sys tem design (e.g. burner choice and placement) and the operating condi tions of the fumace (e.g. crown temperature) . The mechanism of this accelerated conosion is based on the formati on of an alkali containing sil i cate or calc iu m sil icate slag whi ch is highly dependen t on the concentration o f N a species in the Jilmace atmosphere [1- 5 ). Water vapor in t h e atmo s phere reacts with Na s peci es to f orm NaO H , and the NaO H is pre se nt n ear the silica bri ck interface. Th e NaOH rea cts with the s ili ca a nd l' alcium in th e bri ck to lo wer the equilibrium me lting point , re s ultin g in a Na 2 0-Ca0-Si0 2 s lag whi c h slow ly " di sso lves " the brick . The corrosion process is highly dependent on the temperature , NaOH

**~once ntration**  in th e vapor phase, wat er content , gas veloc ity and calc ium content in the brick.

### Melter



### w 

### that by maintaining



### sufficie?~ **tem~cra~**
**·e** at volatilizatio n, corrosion of



### hc~ .bnck ctown itmaoe und er ox.y-fuc l firing conditions 

### [6). . :d furnaces bas 

### been demonstrated, s ub sta iltlal ls of



### consfn~ction for the crown 

### [7-8).



### ~ondcd na or fused cast 

### AZS) show excel\cnl res .IStance nation. However , these refractory matenal 

### ore (more . tecl infrastructure required) 

### nd arc 10 

### install . One tactic ro address 

### the les than st 

### advantages over other alternatives has 

### been ijmi ze the CaO concentration. 

### Tl.te presence



### ~fa l f 

### a calcium illcal e slag in whtch



### th~ **ca~cmm** il.g. 

### The alkali results in further redu c tion 

### m



### ~e :ausing the lag to 

### nm. By

**redu~ing** the CnO Ill



### ~ in 

### a larger, effective Ol>erntmg range (e . g . I to traditiona l silica 

### [ 9 J. materials for oxy-fuel



### fire~ **glas~** . fumnces· cri tical role in 

### fumace integnty. Jltca crown sr

ruction practice s to minimize



### joint~ Wld by the during the furnace campaign. Alkali

**vapo~** 

### can 

### e regime in whic h sing devel?ps. and to : ms age on the crown is critical to mamtam uffictent e also critical to reduce a species volatilization from the melt is 11 

### function of

**temper~t~re,** 

### gas 

### .s burners should be designed and posiitoncd to



### ,~ proper temperature disrribuLion thr oughout the :crnative materials, combustion technology and modem, oxy-fue· l fired container g lass furnace. tonlic operation of 

### a soda-lime glass



### fu~tac~ a I. [1 0] sugge ted 

### a number oF goal or obJii:Cttvcs

.y-fuel furnaces , an d this 

### li t 

### can be expanded for •le I . 

### While these goal : 

### are mo tly .c ommon ensc valuate tlJese hems during any maJor ch ange to 

### a Operational Experience of an Oxy-Fuel Fired Glass Melter Table 

### 1. Objectives for proper design and operation of an oxy-fuel glass metter Design/Operating Consideration: Goal: Investment Cost Minimize refractorv costs relative to performance Life Expectancy Maintain or improve upon "tvoical" life comoared to air-fuel Materials Investigate alternative materials or improvements on available materials Construction and Heat-up Utilize quality materials, stay true to fabrication drawings, minimize possibility of joint expansions Operation Maintain proper temperatures and utilize correct tools to optimize energy and environmental footprint (e.g. electric boost and burners) Operating Cost Improve competitiveness by designing system to minimize operating cost Maintenance Observe system carefully throughout operation, identify issues early and proactively repair Burners and furnace layout Utilize burners, burner positioning and flue positioning to minimize volatilization and maximize heat transfer Grupo Pavisa in Naucalpan, Mexico, has worked to optimize these objectives on an oxy-fuel container furnace (Furnace 14) built in early 2000. This fumace was built to replace a smaller oxy-fuel glass melter. The furnace specifications are shown in Table 2. 

### One of the major goals of this furnace design was to implement a potential improvement on typical silica crowns by utilizing a low lime silica brick which was specifically manufactured as a single production run for this furnace. The reduced CaO content (approximately 0.8%) was expected to reduce crown corrosion while maintaining a reasonable cost for the material and traditional silica crown construction practices. Table 3 shows a comparison of the basic properties of a conventional silica brick against the new, low-lime silica material used in Furnace 14. Table 2. Operating and design soecifications for Fumace 14 Grupo Pavisa) Parameter Value Glass: Soda-lime, flint Melter Area: 527 

## fiT (50 m") Aspect Ratio: 2 . 2 Nominal Pull Rate: 165 tod (150 t/d) Electric Boost: 600kW Fuel: Natural Gas Oxidant: Oxygen- Onsite VPSA Nominal Cullet Ratio: 50% Average 2779 °F (1530 °C) Minimum 2712 

### op (1489 °C) Maximum 2835 °F (1557 °C) Ave. Specific Energy : 3.8 MM BTU/ston (952.2 kcal/kg)

70th Conference on Glass Problems · 35Operational Experience of an Oxy-Fuel Fired Glass Melter

. Burners: Wide Flame (6), opposed

Crown Material: Low-Lime Silica 

### (0.8% Ca.O) Average ofHHV of natural gas and electnc boost over furnace campaign 

## T ST

ablc3. 1 tea refractory_prQgcrtics Commercial Silica Low Flux Factor 

### Low Lime Silica Bulk Densitv, kg/m' 1794 

### 1875 % ADoaront Porosity 23 .0 t8.0 Modulus of Rupture At2l°C,MPa 6.2 4.3 Reheat Test at 

## tsoo•c % Linear Change +0.2 +0.2 Chemical Analysis 

### Silica 95.9 98.4 Alumina 0. 2 0.2 

### lro110xid e 0.6 0. 4 Lim e 3.0 0.8 

### 4/ka/ies Tr 0.1 

### Others 0.2 0.1 Silica Ph ases 

### Ouartz <1 <1 Cri

s t 

### + Trid . 75+ 75+ 

### Amol· nhous N.D. N.D. 

### The combustion system 

### was also designed to minimize refractory con·osion. The furnace utilized six (6) Prax:air Wide Flame burners in an opposed arrangement. The burners were specifically designed to minimize 

### gas momennuu near the melt surface while maintaining good heat transfer characteristics and low NOx emi. sions. With this combination of materials and combustion system, Grnpo Pavisa hoped to maintain **prop~:r** fumace life while optimizing operating costs. The earl y results (frrst 

### 45 months) of operation of this furnace have been previously described and the construction details outlined 

### [10]. For bu ine ' s reasons , Grnpo Pavi 

### a made the decision to end the furnace campaign and complete 

### a cold repair in April 

### 2009 aficr 

### 9 years and 

### 4 month of operation . . A summary of thi furnace campaign i s pre cntcd below . RESULTS: EXPERIENCE DURING SERVICE LIFE 

### FURNACE OPE RATING 

### SUMMARY Furnace 14 started operation in late January 2000 and concluded operation in April of 2009, making approximately 

### 440,000 ton of glass during the campaign. Figure I illu trates the pull rate and cullet ratio of the furnace over a 110 month period leading up to the hutdO\Yll and sub equent cold repair. Over the ftrst 60 months of operation production gradually increased to the nominal capacity of 

### I SO tid . ear the end of the campaign the pull mte exceeded the nominal capacity reaching a

36 · 70th Conference on Glass Problems Operational Experience of an Oxy-Fuel Fired Glass Melter maximum of 162 t/d and production remained hi h until th 

### ft furnace also varied significantly over the fu gl'fi . le rmace 

### shutd~wn: The cullet ratio of the mace 1 e, mam y due to the avallabt!Jty of external cullet.
180 

# ----- 100 90 140 80 

# ! 120 70 

### E. 100 60 

# l

**~** 0 

# "' 0:: 80 

# ,..,..., 60

**~** :; 

# " .P"' 2 a. 60 

# '""\/', I 40 :; u (I I 30 40 \I 

# • 20 20 10 0 0 20 40 60 80 100 Months of Operation Figure I. Furnace 14 Pull Rate and Cullet Ratio versus Month of Operation Furnace operating conditions were ad· t d d · 

### h . . the production lines and to res 0 

### ~us e unng t e campaign to satJsfY requirements from electric boost during times 

## of]~:! **~ub:~~~~u~anables** changes. This included a general increase in Figure 

### 2 illu tratcs the energy input · 

### ft 

### 1 d . boost was used - omewhat 

## sporadica~:; **u:~o~~l ~~~:c~c**  boost over . the life of the fumaee. The electric



# ~~~dthe**L;;n~~~~~t ~~:a~~n~h:**  **~~~:c~~~o:~~n~ .**  watter t:; e

# e~:~;~~!:; **:~s~~:~~~n c;:~:g** **~~tfu~~~i~~** electrode area of the tank 10 avoid 1 

### ys em. ot work _ also had to be perforrned in the rate for the combustion system 

## hal~~ b leaks and Juarrullee contmued operability. Thus, the firing temperatures (up to 2900 oF or 1595 

### •c). e mcrease to compensate which resulted in higher crown

70th Conference on Glass Problems
. 37Operational Experience of an Oxy-Fuel Fired Glass Melter
40.0 35 . 0

**~** 30.0



# ~ 25.0 :::;; 

### !. 20.0

**~** [! 15.0

**~**
... 10.0 5.0 20 40 8l) Months of Operation 1 - · •- Natural Gas --e- Electric Boost 

### IElo ctrode Folluro 100 1000 900 BllO 700 §' 600 ;!. 

# 1 500 Ill u 400 :; u 300 

## w 200 100

Figure 2. Flll1lace 14 Fuel Energy Input and Electric Boost versus Month of Operation Analysis of the energy efficiency of the furnace over time requires normalization to compensate for changes in pull rate, cullet ratio and electric boosting . Figure 3 illustrates the normalized specific energy consumption in MMBTU/short ton of glass and melting temperature versus the months of operation of the furnace. The normalization of the specific energy 

### was based on 

### a c onstant pull rate of !52 li d 50% of cutlet ratio and no electric boosting. It was also necessary to correct for a n inc. re mcnt observed in the glass temperatures at higher loads. After applying 

### all COITection 

### an in crease 

### of around 7% in the specific energy consumption over the course o f the furnace life wa obsorved (or 0.77 % / y on linear bases). A careful review of the historic operating data of furnace 14 has revealed that most of the increment on the energy consumption is due to an increased amount of parasitic air leakages going into the furnace, which was calculated to be about 22% of the flue gas flow rate from the fuel and oxygen flow rates and the flue gas 

### 02 concentration. Parasitic air leakages are typically less than 5 tolO% of the flue gas flow rate for a new furnace or an old furnace with extensive sealing of open joints. If the specific energy consumption were corrected for the increment of parasitic air, the increase in the specific fuel consumption would be less than 1-2% , which would correspond to the furnace aging loss attributable to the increased wall heat losses.



### 38 70th Conference on Glass Problems Operational Experience of an Oxy-Fuel Fired Glass Melter
6 .00 5.50 

### c



### ~ iii 5.00 :::;; 

### !.

**~** 4 .50 l; c w u !E 4.00 u

**~** en 3.50
20 40 60 Months 80 100 1 , 600
1. 55 0 

### e

**~** 1 , 500 1;



### ~ E

**~**

Figure 3. Furnace 14 Specific Energy Consumption and Melting Temperatures versus Month of Operatwn .
LOW LIME SILICA CROWN RESULTS The pl ant expectations for using the low-li me silictt brick as crown material were to h crown th at last 

### a 

### full · · 1 • • • ave a . . campa1gn wnt mmnnal detertoration 

### and few to no hot repairs . Based on the opetratmg expderd1ence from lhe full 

### f urnace campaign , the performunce of the new refractory material me or 

### excec e these ex pee

### tat' o B · k 1 d · · · · . . h 1 n · nc s towc mtntmum detenorahon after more than 9 years of operatiOn Wit oxy-fuel tiring .

70th Conference on Glass Problems 

### 39Operational Experience of an Oxy-Fuel Fired Glass Melter 

### fl three different zones . Zon A wa Figure 

### 4 illustrates three brick ample



### t~kcn from the crown



### ~om d 

### Z ne C 

### was ncar the 

### gin in the vicinity of the batch charge area Zone B was near the ot s pot



### a~ **~** . al brick height of Idischarge point. The dotted line near the top of the



### fi~ure **r~presents** It e



### on~~n f b vtWecn 1-1.3 inches. Examining the men ured height of the remauung bnck rcven corroston o r . e\,liS 

### level of inches (2.5-3.3 em) of material, or a matenal los: : rnte of about 2 . 7to 3.5 mm /yea material loss (or less) was consistently observed throughout the c1own.
Original Brick Height

Zone C- Zone A- Zone B- Hot Spot Glass Discharge Area Batch Charge Area d C Figure 4 . Crown Brick Samples taken from 3 Zones: A- Batch Charging Areas, B- Hot Spot, an - Glass Discharge Area. The temperature of the fumace crown was monitored throughout the campaign , and the profile · d · 

### 1 U rate Figure 

### 5 illustrate the average crown along the length of the furnace vane Will pu ·. 

### II l As might be expected higher temperature prolile along the length of the furnace at varymg



### p~ **~les**

**. e~dting**  condition



### Ul~ crown pull rates resulted . 

### in higher crownC



## tcnhl?C:~~rc ld



## o~:~:: **~~C:H** a?·orption itlto a caldium silicate temperature was htghcr than 1450 , 

### w . 1c s . ou mm1 slag (3].

1560 (.) 1540 

### -1---------'+ 1I 

## " 1§ 1520 -1---- -77'- 

## "' c.



## ~ 1500 

## +----~----------------------

**1** 1480 

# 1--------------------- 1460


### -!---------·~·--· **-··--** 

## ·--

**~----**

**0** _ _ 4 ..., 5- 0 ---1 500 0 50 100 150 200 250 300 350 Distance from Back Wall, in 

## -+--166 TP - 0 - . 

## .:-;-

53T P D - M 4TPD
- -- 12s

**r~ l** 

. · f· tl Back Wall at Various Pull Figure 5. Average Crown Temperature as a Funcuon ofD1stance 10m le Rates
40 70th Conference on Glass Problems Operational Experience of an Oxy-Fuel Fired Glass Melter Maintenance of the crown was not a major issue during the course of the campaign and no repairs were required associated with the performance of the low lime brick. The only problem reported with the crown wa s in the expans ion joint z one s . Fumace 14 had two expansion joint zone s, one close to the charging end and the other close to the refining area . Immediately after the furnace startup , sealing problems were detected at the expansion joints. However, at that time, the magnitude of the fumace gas leakage was not considered impo1tant and the issue was not immediately corrected. After a period of operation, alkali vapors started to penetrate the joint, absorb into a slag layer attacking the crown and cau s ing damage to tlle nearby bricks. Hot repairs had to be made in these areas to avoid losing parts of the superstructure. No additional hot work was required after making this repair. Figure 

### 6 and Figure 

### 7 show images of the crown after cooling the furnace at the end of the campaign. The images illustrate consistent wear throughout the crown, and no significant points of deterioration. The operations team at Grupo Pavisa felt that the furnace could have operated for at least 2 additional years under these conditions. However, the decision to rebuild the furnace after only 9+ years of operation was primaril y due to market conditions and a de s ire to modify the fumace to enable the production of different product lines. With the cmTent global economic downturn , this was an ideal time to take 

### a fum ace outage. Also, the tank refractory contained higher levels of chrome than desired for color requirements of ce11ain product lines. Finally, the loss of electric boost resulted in an increase in furnace temperature due to increased gas firing, and the team felt it wa s important to restore electric boost capacity to properly balance furnace energy input. It s hould be noted , however , that even though a 40-50 

## o c increase in crown temperature occmTed upon loss of electrodes, no deleterious effects were observed on the crown or other pa11s of the superstmcture.

Figme 6 . Fumace 14 Crown During Demolition- View 1

70th Conference on Glass Problems 41Operational Experience of an Oxy-Fuel Fired Glass Mette r

BURNER Grupo Pavisa fumace 

### 14 i equipped with ix of Praxair's first



### gene~a **ion** Wide



### Fl~me **mers** ins talled 

### in an oppo ed an·angement . The 

### c burners were designed to be 

### a un pl c and flex t b le p t ece of combustion equipment and Grupo Pavisa selected this bu mer due to it s unique attribute . The



### b~ **rner** generates a wide n ame pattern that covers up to 200% more of the glass surface than convenu onal oxy-f ue l burners . In addition , t he large , low velocity , lumino us flame allows t he bumer to tra n sfer hea t mo re efficien tl y and prevent hot po t o n the g lass s u rface . uffieicntly 

### high burner e lcva u on together wi t h low flame veloc ities a nd low momentum minimize alka li vol atilizat ion !Tom the g la melt resu lti ng in less furnace upersiructure co t Tosion , l onger furnace life , and redu ce? .

### p~c **ul atc**  formation . Figure 

### 8 s hows a s c hem ati c of the firs t genera t ion burner . 

### In order to mt llltntze NOx formation , oxygen is staged thro ugh a e parate set of nozz les under the f ue l nozzle . The burne rs were fi red betwee n 

### 2 .5 to 

### 6 . 5 MMBtulhr 

### (0 .75 to 

### 1 .9 MW) .



### ·

# ..



# ~ 1 

# o~~ .. Jj ... 

# ..

**~101> fl**  

# . . $ 0 

# H I

**[''~'JA J**  

# 1: I

# ©•tt

. ' 

# . . Figure 

### 8. Pra x air ' s Wide Fl ame Burner First G e neration (From left to rig ht: ba ck , top & side and front) A second generati on of W ide F lame Burner was recently



### introd **ce~** to fu rt her



### rn **pr ove**  burner performa n ce and to min imize main t enance requirements. Th new gc nerauo n bu rner 

### :o~o~a **es** an ev olut i on in Dilute Ox ygen Combu stion technol ogy, includiJ1g deep l y staged oxygen 

## mJe~tlon and min im ized gas , ,c loc ities nea r the bu rner face . The result is a rob ust and d u rab le burner w tth all

_ tlte positive characteri tics of the prev iou gencmtion a we ll as the benefit of advanced flame dynamtcs . F i

g ure 9 illustrates a schematic view of the second gen eration burner. 42 · 70th Conference on Glass Problems Operati onal Experience of an O xy-Fuel Fired Glass Melter

Fi gure 9 . Prax air ' s Wide Flame Burne r ( Se cond Generati on) Grup o Pav isa tes ted t wo of the ne\ generation burners in positi on 

### I (Ri ght and 

### Left) of its furnace 14 from Ju l y 2008 to 

### th furnace shut down in April 2009 . Tota l eva luat ion tim e 

### wa appro imate ly 9 m0 1 1ths (37 weeks). D uring this time t he burners were fi red continuous ly at about 5 M I.Btulhr (1.5 MW) wi t hou t needing any maintenance. Figure 10 ill ustmte s the installed view o uts tde t he 

### furnace ( left) and the b urner in operation from the interior view of the fumacc L!U'ough a viewp ort (right) .

Figure 10 . Wide Fl ame Burner Se con d Gen er ation Prototype at Grupo Pavi s a Furnac e 14 . Th e flam e shape a nd he at transfer ch aracteristics were consistent with the first generatio n design, m a king sub stitutio n a seamle s s proces s. Both burners were c arefully insp ec te d after the shut down.

**~h e**  **re ul~s**  of th e inspection revealed that t he burners were in exce ll ent condi tion wi. tll no ig n of detenoratt on m the burner blocks or other parts . These res u lts indicate 

### that t he bu mcrs ho ul d 

### be

**n~le** to operate witho ut mni nte nance for 

### a much lo nger period of time. Grupo Pavisa was ver y p leased 

### \\'II? t h . perfom1ance of the new burner design and p lans to replace t he ex ist in g burn ers wit h t he new 

### de

**1g~** 

### m the near furore . Anotl1er test of the next generation burner is cul1'en tl y underway on 

### a coma mer g l a f urnace at another site, with simi lar o b ervation ru1d re ults to date. . CON CLUSION I n t hi paper, t he operationa l experience of an oxy-fuel container glas s furnac e h as b een

**~re ent**  **ed** i . nc lud in g 

### i. ues around materia l e lect. ion , construction practi ce , and operational practice .

. he op c
_ rnu.ng **~a'."patgn** of Furnace 14 at Grupo Pavisa demonstrates the potential for a n ew type of sth ca bn ck to hum crown corro io n . This low -lim e s il ica brick conta ined rela tively t ow level ofCaO (-0.8%) while maintaining th e general phy s ical and thern1odynamic attrib ut es of s tandard si lic a bri ck. Th: furna ce also untilized low-momentum Wide Fl ame burners to reduce vo latilizatio n off the melt whtle mai t · · d h " ' n ammg goo eat trans, er and emi s sions ch ara cter istic s . Implementation of th ese new 70th Conference on Glass Problems · 43(perience of an oxy-Fuel Fired Glass Melter 

### minimal crown deterioration over the course of

:ens (TNO) and Enrique Solorzano (PAVISA)

**~r.** 

### lmic Analysis of Silica Refractory Corrosion in ochemical Society. 

### 148(2) 859 , 200l. . . 

### i corrosion of up erstructure refractory bncks m a/ Symposium o n Glass Problem', eptember 4- 

### ms of alkali vapours with silica based refractory ;msfer, Glass Technology, 

### 46(6) 371, 2005.



### Jmeri~al modeling of alkali volatization in glass ·ed furnace design .' Proceedings of the 

## 4'" tsion & Proces lng of Glass, 1995 , Wiirzburg, 

### •lass melting technology - Experience, evolution

**~I** 

### Commission on Glass, September 

### 21-25, 2003, d container glass furnace with silica crown- 14 on Glass Problems, 

### Ed. C. 

### H . Drummond 

### IlL 3-11. :eadrick, R .E. Moore. J.G . Hemrick, and J.M,; 1 

### der oxyfuel environment." Proceeding of the 

## 1 tsion & Processing of Glas . Jul y 

### 27-3_1 , 2003, -.P. Seward 10 , H.A. Schaeffer. W esterv ille, OH: namic analysis of alumina refractory corrosion by lting furnaces," Journal of The E/ectrochemtcal 

### and HE Wolfe "New silica refractory for lre, . . · 

### Journal - A. T.I. V. Conference 

### XV. Parma, Italy, 

### M .A . Nelson. "A review of improved silica crown

**~ss** 

### melters ." 64 1 h 

### Conference on Glass Problems, 

### merican Ceramic Society, 33-42, 200 4 . ,nsional modeling of alkali volatilization/crown lnnual Meeting ofthe American Ceramic Soctety, 

### Jnsiderations and modeling of the glass metter International Congress on Glass,Madrid, Spain, 

### 'Reduction of alkali volatilization and refractory •wtional Glass Journal - A.T.I. V. Conference 

### XV. romise in service." The Glass Industry, 

### 80(8), 23

- C'MON, LEVEL WITH ME Terry Berg Sr. Pr. Process Engineer CertainTeed Saint Gobain ABSTRACT There are many factors which affect glass level stability. Some of these include the type of charging system, the reliability and sensitivity of the level detector, the type of control logic loop and the stability of the process itself. This paper will only consider the various types glass level sensors and the pros and cons associated with each. A summary table is provided at the end. When it comes to sensing changes in glass level, there are many different methods available from which to choose. They can be broken down into two basic categories , i .e . contact and non-contact. The contact types are oscillating probes, static conductivity probes and bubble pressure tubes. The noncontact types include nuclear, pneumatic, laser and optical. They vary in cost of installation and operation, frequency and cost of maintenance and system requirements. Since the various processes and glass compositions used in the industry have different requirements, this paper will look at the advantages and drawbacks of several techniques with the aim of helping you with the selection process. This information was derived where ever possible from interviewing engineers who have hands-on experience with these pieces of equipment installed in their plants. YMMV! ( For nontexters, "Your mileage may vary ") Oscillating Probes These are probably the most commonly used level sensing devices in use today and there are several different makes and installation methods. The one pictured here is installed directly into the forehearth through the breastwall. Some plants will have a separate alcove off to the side of the refiner or forehearth but the principle is the same. The oscillator moves a platinum-tipped probe down until contact with the glass is made. This completes an electric circuit telling the batch charger to speed up or slow down depending on the glass level and tells the oscillator to raise the probe to start another cycle. This process is very straightforward but not without its problems. The unit shown here has a ceramic tube having a platinum tip. During a recent upset, the temperature in this section of the forehearth went up 200°F and the tube began droop. The batch charger interpreted this as a high level reading and stopped charging. The level dropped a couple of inches before the effects were seen in the process downstream. Fortunately, this was corrected before the electrodes became exposed. The same unit in the sister plant has a water-cooled probe which has never drooped. If the temperature near the probe goes down and the g las becomes tncky, the probe will start to pull "stringers" or get a build up on it and again the batch charger will think the glass leve l i high and slow down or stop . To prevent this, the temperatu re in this zone hould be monitored c losely and the probe should be visually inspected periodically to make sure th!ll no build up is ocomring. 45

# 70th Conference on Glass Problems

A Collection of Papers Presented at the 70th Conference on Glass 

# Problems The Ohio State University, Columbus, Ohio October 11-12, 2009
Edited by 

# Charles H. Drummond, Ill

The American Ceramic



## A' **~**



## Society~~



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# Contents

Foreword Preface Acknowledgments GLASS MELTING 

## Rapid Refining of Submerged Combustion Melter Product Glass David Rue, Walter Kunc, John Wagner, Bruno Purnode, and Aaron Huber 

## Modeling the Quality of Glass Melting Processes . . . Adriaan Lankhorst, Andries Habraken, Mathi Rongen, Ph1l1p S1mons, and Ruud Beerkens 

## Process Optimization of the Glass Forming Process by Advanced 3D Forming Models Erik Muijsenberg 

## Operational Experience of an Oxy-Fuel Fired Glass Melter Using an Improved Silica Crown and Wide Flame Burners . Alonso Gonzalez, Wladimir Sarmiento-Darkin, John T . Brown, Len Switzer, Euan Evenson, Sho Kobayashi, and Cuauhtemoc Lagos 

## C'mon, Level with Me Terry Berg 

### THE FUTURE OF THE GLASS INDUSTRY AND ENVIRONMENTAL REGULATIONS 

## How Big is My Carbon Footprint? Todd J. Seifried, Christopher J. Hoyle, and Douglas H. Davis 

## ix xi xlii



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